Self-loop in graph

### What problem does this feature solve?
This feature would solve that it is possible for an edge of a node to point to the node itself. I want to generate a graph that shows the schema of my Neo4j database and some nodes in the schema point to themselves. This is because of hierarchical structures in one label. For example as a Disease, cancer is very general and malignant mixed neoplasm is a more specific kind of cancer. So these two nodes are connected with a relationship is_a.

Example: https://imgur.com/a/cFJyn14

### What does the proposed API look like?
It should be like it is now: nodes:[{name:'Disease'}],edges:[{source:'Disease', target:'Disease'}]
and generate then the self-loop.